1. Field of the Invention
This invention relates to a melt receiver for a semiconductor single-crystal manufacturing device.
2. Description of Related Art
The substrate of a semiconductor component is mainly made of single-crystal silicon with high purity. The method for manufacturing single-crystal silicon with high purity is chiefly the Czochralski Method (hereinafter referred as the CZ method). FIG. 5 is a partial schematic cross-sectional view showing an example of a device for manufacturing semiconductor single crystals by the CZ method. As shown in FIG. 5, within the main chamber 9, a graphite crucible 10 is disposed on the upper portion of a crucible axis 5 which is capable of rotating and moving upward or downward. Furthermore, a cylindrical graphite heater 6 and a heat reserving cylinder 13 made of adiabatic material are disposed around the graphite crucible 10. The main chamber 9 constitutes of a container made of two-layer stainless steel. Cooling water is circulated within the space of the two layers of stainless steel so as to keep the temperature within the furnace at a proper value (furnace: chamber providing a crucible, heater and etc.). Furthermore, a melt receiver 14 made of adiabatic material (such as carbon fibers) is installed on the bottom of the main chamber 9. The melt receiver 14 is provided with a hole 14c and a through hole through which an electrode 15 of the graphite heater 6 is inserted. A discharge pipe for expelling SiO gas coming from the melt 8 with carrier gases out of the manufacturing device is inserted through the hole 14c in the melt receiver.
Polycrystal silicon in lumps is fed into a quartz crucible 7 accommodated within a graphite crucible 10 and heated by the graphite heater 6 to be melted into melt 8. A seed crystal installed within a seed chuck 16 is dipped into melt 8. Then, the seed chuck 16 and the graphite crucible 10 are driven to rotate in the same or opposite directions, and at the same time the seed chuck 16 is lifted to grow a silicon single crystal 17. The parts such as the quartz crucible 7, the graphite crucible 10, and the graphite heater 6 are designed based on the temperature distribution within the furnace and the heat history of the silicon single crystal 17. However, it does not mean that everything is taken into consideration when melt 8 is solidified due to an unforeseen trouble during lifting of silicon single crystal. The solidification of the melt 8 will cause damage to the quartz crucible 7 due to expansion of the volume of the melt 8 and consequently bring about outflow of the melt 8. Under such a circumstance, the melt receiver 14 is not of the structure capable of absorbing all of the melt 8. Furthermore, it is neither of the structure capable of preventing damage to the bottom of the main chamber, which damage is induced by dropping of the broken quartz crucible or the broken graphite crucible. If the outflow of the melt 8 or drop of the debris of the broken quartz crucible or the broken graphite crucible impairs the bottom of the main chamber, there exists a danger that the cooling water circulating within the walls of the main chamber will cause a steam explosion.